Magnetic shuttle detector



Sept. 1 l, 1951 Filed Feb. 21, 1950 R. w. WOLKE 2,567,751

MAGNETIC SHUTTLE DETECTOR 2 Sheets-Sheet l Inventor: 'RiChaTd w. Wolke,y W

His Attorn ey.

Sept. 11, 1951 R. w. WOLKE MAGNETIC SHUTTLE DETECTOR 2 Sheets-Sheet 2Filed Feb. 21, 1950 4-AAAAAAA hqam .EDUEU lllA Wm JmW W d mr a I m m Rwk y WW5? His AttOP'ney.

Patented Sept. 11, 1951 MAGNETIC SHUTTLE DETECTOR Richard W. Wolke,Schenectady, N. Y., assignor to General Electric Company, a corporationof New York Application February 21, 1950, Serial No. 145,337

2 Claims.

My invention relates to textile weavin looms and more particularly toprotective apparatus for the detection of abnormal shuttle motiontherein.

In conventional weaving looms the shuttle which carries the weft yarn toand fro across the warp yarn may, for a variety of reasons, be deflectedor retarded in its normal flight, so that it fails to box properly atthe end of it flight. If

the shuttle is not boxed properly when he lay beam and its reed swingforward to press the weft yarn into the fabric, the shuttle is forcedinto the warp yarn causing breaking thereof and necessitating expensiveand time-consuming repairs. Moreover the continuity of properly wovenfabric is, broken and in the case of a closed fabric, such as a dryingfelt for a papermaking machine, the fabric is ruined for its in tendedpurpose.

Heretofore mechanical feelers have been employed to determine whetherthe shuttle has boxed at the proper point in the loom cycle and tocontrol the position of stop daggers on the lay beam. If the shuttle isdelayed in arriving, the daggers, which are normally moved to aninactive position in response to boxing of the shuttle, remain in theiractive position and by interference with the breast beam impede forwardmotion of the lay beam. Through an associated actuating mechanism, poweris removed from the loom and a brake is applied. Since detection by thefeelers occurs near or at the end of the shuttle flight, and thereforelate in the loom cycle, if it is necessary to halt the progress of thelay beam relatively high forces are required to produce rapiddeceleration thereof. The shock effects resulting from such deceleratingforces are responsible for a considerable amount of costly damage tolooms and place a limitation on maximum loom speeds.

Recently magnetic detecting devices have been employed whereby theposition of a shuttle may readily be sensed at any desired point in itsflight. An electrical signal indicative of the position of the shuttlerelative to the cycle of the loom is thus provided to actuate a stoppingmechanism in the event of abnormal shuttle motion. Such a signal may bederived at an earlier point in the loom cycle than is possible withmechanical feelers, and accordingly a greater period of time isavailable to stop the loom and correspondingly reduced deceleratingforces may be applied thereto.

In utilizing a signal from a magnetic shuttie detecting device it isnecessary to interpose a suitable control apparatus between the detectorand the particular stopping means employed. The latter may be, forexample, dynamic braking of electric driving motors. It is the functionof the control apparatus to effect comparision of the progress of theshuttle in its flight with the time cycle of the loom, and to effectstopping of the loom in the event of faulty shuttle motion.

It is accordingly a principal object of my invention to provide a newand improved control apparatus which is particularly suitable for use inlooms for the purpose of effecting shutdown thereof in the event offaulty shuttle motion.

It is a further object of my invention to provide a new and improvedcontrol apparatus for use with a magnetic detecting device to detectfaulty shuttle motion in weaving looms and to effect stopping of thelooms in the event thereof.

In accordance with a preferred embodiment of my invention I provide anarrangement whereby a pulse from a magnetic detector, positioned to beresponsive to motion of the shuttle relative to the lay beam, iscompared with motion of the loom by the use of a switching deviceactuated by the loom. An electromagnetic device, such a a relay, isnormally energized through the switching device. The latter is openedfor a short period during each loom cycle, however, and during thisperiod the electromagnetic device is normally energized through anelectron discharge device which is rendered conductive by means of apulse from the magnetic detecting device. If the pulse from the detectordoes not occur at the proper time in the loom cycle, or, in other words,does not occur in synchronism with opening of the contacts of theswitching device, the electromagnetic device is deenergized to effectstopping of the loom through a braking device.

My invention will be better understood from a consideration of thefollowing description taken in connection with the fiigures of theaccompanying drawings, and its scope will be pointed out in the appendedclaims. In the drawings, Fig. 1 is a schematic elevational view of aportion of the lay assembly of a loom; Fig. 2 is a cross section takenalong line 2--2 in Fig. 1; Fig. 3 is an enlarged view of a magneticdetecting device shown generally in Fig. 1; and Fig. 4 is a schematicdiagram of a magnetic shuttle detecting apparatus constructed inaccordance with my invention.

Referring now to Fig. 1, there is shown an elevational view of the layassembly I of a weav- 3 ing loom. Shown in conventional relationship arethe lay swords 2 with their journals 3, the lay beam 4, the crankshafttogether with journals 5 and cranks 1, and shuttle boxes 8 and 3. Amagnetic detecting device III is positioned in the lay beam near thepath of flight of the shutt e II. A rotary switch assembly I2 ispositioned at one extremity of crankshaft 5 and is arranged to have itscontacts actuated in response to rotary motion of shaft 5. Magneticdevice It and switch I2 will be more fully described hereinafter.

Fig. 2 is a cross section taken along the line 2-2 of Fig. 1 showing, inaddition to certain of the elements of the lay assembly shown in Fig. I,the reed I3 and portions of the heddle I4 and the warp yarn I5. Theextreme rearward and forward positions occupied by the lay assmbly inthe operation of the loom are shown, respectively, by solid-line andbroken-line views of lay swords 2, lay beam 4 and reed I3, theseelements being given prime numerals in the forward position. The shed I5is formed by groups of alternate strands of yarn, which are separated byaction of the heddle, and reed I3 when the lay assembly is in itrearward position.

Shuttle I I is thrown to and fro across the lay beam by action of thepicker sticks (not shown) carrying the weft yarn through shed I5.Following a flight across the lay beam, shuttle II is boxed in eithershuttle box 8 or 9 (shown in Fig. 1) and the lay assembly is movedforward to force the weft yarn into the fabric I! at the fell I8. Theaction of the lay assembly and shuttle, as described, is conventional innature and is included for the purpose of assisting in understanding myinvention.

Attention is now directed to Fig. 3 which is a cross section of magneticdetecting device ID, as positioned in lay beam 4, and a portion ofshuttle II showing a magnetic element I9 embedded therein. Device IDcomprises a pair of coils 20 and 2| positioned on legs 22 and 23 of agenerally U-shaped core 24, the center portion of which is a permanentmagnet 25. Legs 22 and 23, which are preferably formed of a plurality ofrelatively thin laminations of a magnetic material such as siliconsteel, are engaged with magnet 25 at joints 26 and 21 in a manner toassure substantially no air gap between magnet 25 and legs 22 and 23.The assembly of coils 20 and 2I and core 24 is positioned on anon-magnetic base plate 28 in a cavity 29 of lay beam 4 and may besecured to the latter by screws or any other suitable fastening device(not shown). The depth of cavity 29 is such that coils 20 and 2| and theextremities of legs 22 and 23 are positioned slightly below the surface30 of lay beam 4.

Shuttle II, in its flight across the lay beam, generally is in contactwith the surface formed by the strands of warp yarn I5 which are shownin cross section in Fig. 3. A gap 3I exists between the upper surface 30of lay beam 4 and lower surface 32 of shuttle II. Magnetic element I9,which is positioned in shuttle I I to be flush with surface 32, is arelatively thin member which may be made up of laminations of a magneticmaterial such as silicon steel. The exact size of element I9 isdependent to a large extent on the length of gap 3| and the speed ofshuttle II and may be varied to suit the gap encountered in weaving aparticular fabric.

Attention is now directed to Fig. 4 which is a functional schematicdiagram of the control apparatus to which signals are supplied frommagnetic detector I0 and rotary switch I2 to effect stopping of the loomin the event of faulty motion of shuttle II. Rotary switch I2 comprisesa fixed contact 33 and a movable contact 34, the latter being fixed toan arm 35 arranged to rotate about a pivot 36. Arm 35 is normally forcedby a compression spring 31 into engagement with a cam 38. Cam 38 isfixed on a shaft 39, and the latter is connected to crankshaft 5, asshown in Fig. 1, so that cam 38 is rotated by motion of shaft 5. Cam 38is provided with a raised portion 40 at one point on its periphery.Contacts 33 and 34 are forced into electrical engagement with each otherby the action of spring 31 against arm 35 except when raised portion 40of cam 33 engages the opposite side of arm 35. In the latter case,contacts 33 and 34 are forced apart and the electrical engagementtherebetween is broken. Electrical connections to switch I2, for use inthe control apparatus, are made to arm 35 and a mounting block 43 towhich contact 33 is fixed. Cam 38 is preferably formed of an insulatingmaterial and the conducting elements of switch I2 are mounted on asuitable base 44 of an insulating material.

The control apparatus shown in Fig. 4 comprises principally a pulserectifier circuit 50 provided with pulse signals from magnetic detectorI0; an amplifier and pulse-shaper circuit 5I to modify signals fromrectifier 50; and an output circuit 52 provided with signals from rotaryswitch I2 and circuit 5|, and arranged to actuate a magnetic switchingdevice. 53. Switch 53 may be connected to any suitable loom-stopping arrangement, such as a dynamic braking circuit (not shown).

Rectifier circuit 50 includes an electron discharge device 54 having anindirectl heated cathode 55, a heater 5'! and an anode 58. One terminalof heater 5! is connected to ground and the other terminal is connectedto the positive terminal of a direct-current source shown as a battery59. The negative terminal of battery 59 is connected to ground through aswitch 5|. Windings 20 and 2I of magnetic detecting device III areconnected in seriesrelation in an aiding sense. One end of the seriescombination of windings 20 and 2| is connected to cathode '55 and theother end is connected to ground. A resistance BI is connected betweencathode 55 and ground. A capacitor 64 and a variable resistance 65 areconnected in parallel relation between anode 58 and ground.

Amplifier and pulse-shaper circuit 5| includes an electron dischargedevice 56 having a pair of indirectly heated cathodes 61, a pair ofheaters 68, a pair of anodes 59, and a pair of control electrodes 10.While device 65 is shown as a dual triode, it will be understood that asingle triode may be employed if desired. Heaters 68 are connected inparallel relation between ground and l the positive terminal of battery59. Cathodes 51 are connected to ground. Control electrodes II areconnected together andv are connected to anode 58 of device 54 through acoupling resistance II. Anodes 69 are connected together to form ajunction point 12 and are connected through a pair of serially connectedresistances I3 and I4 and a time-delay switch 15 to the positiveterminal of a battery 15. The negative terminal of battery I5 isconnected to ground through switch 60. Switch I5 is of the thermallyactuated type and is provided with a heater I1 and a pair of normallyopen contacts 13. The latter are arranged to be closed by a thermal deavice, such as a bimetallic strip, in response to heating thereof. Heater11 is connected between ground and the positive terminal of battery 56.The junction point between resistances 13 and 14 is connected to groundthrough a capacitance 19. Junction point 12 of anodes 69 is connected toground through the series combination of a' capacitance 80 and aresistance 8|.

Output circuit 52 includes an electron discharge device 82 preferably ofthe gaseous discharge type having a cathode 83, a heater 84, an anode85, a screen electrode 86, and a control electrode 81. Heater 84 isconnected between groundand the positive terminal of battery 59. Controlelectrode 81 is connected through a coupling resistance 9| to thejunction point 92 between capacitance 80 and resistance 8|. Electrode 81is also connected to ground through a capacitance 93. Electrode 86 isconnected to cathode 83 and the combination thereof is connected to thecommon point 88 between a pair of resistances 89 and 90, the latterbeing connected in series relationship across the output of battery 16in a potential-dividing arrangement. More particularly, the seriescombination of resistances 89 and 9|] is connected between ground andthe common point 94 between switch contacts 18 and resistance 13. Anode85 is connected to point 94 through the series combination of actuatingcoil 95 of magnetic switching device 53 and also a pair of normally opencontacts 96 thereof. Device 53 is preferably a sensitive relay such asthe type commonly known as a telephone relay. A resistance 91 and 2.ca.- pacitance 98 are connected in parallel relation with coil 95. Oneterminal of rotary switch I2 is connected to the common point 99 betweencoil 95 and contacts 96 and the other terminal of switch I2 is connectedto ground. Switch 53 is provided with a second pair of normally opencontacts I00 which may be connected in any desired loom-stopping circuit(not shown).

In operation, shuttle travels to and fro across lay beam 4 causingmagnetic element 9 to be moved across magnetic detector ID. A magneticfluxis normally established by magnet 25 in a series path including leg22, the air gap between the upper extremities of legs 22 and 23, and leg23. The path of flux between legs 22 and 23 is shown approximately inFig. 1 by magnetic flux lines |0|. As magnetic element I9 passes throughthe air gap between legs 22 and 23, the reluctance of the air gap ismodified, thereby causing a change in the fiux established by magnet 25and causing pulses of voltage to be induced in windings 20 and 2| ofdetector H). The passage of magnetic element l9 across detector I!)initially causes an increase in the flux circulated by magnet 25followed by a decrease of the flux, and hence the induced pulses areinitially positive and then negative, or vice versa, as shuttle l andmagnetic element l9 approach and then leave the vicinity of detector H).The polarity of the pulses is independent of the direction of travel ofshuttle While a single 6011 may be employed in detector Hi, the use of apair of coils connected in series relation, as in the presentembodiment, provides a higher voltage pulse which is more readilyutilized in the control apparatus.

In initially placing in operation the control apparatus shown in Fig. 4,switch 60 is closed to apply voltage from battery 59 to heaters 51, 68,84 and 11 of electron discharge devices 54, 65 and 82 and time-delayswitch 15, respectively.

thereby, thus permitting the negatively induced voltage ofwindings 20and 2| to be impressed on resistance 65 and capacitance 64. -Capacitance64 is immediately charged to the voltage impressed thereacross, which ispreferably on the order of 4 or more volts. As the amplitude of thepulse voltage returns to zero, capacitance 64 discharges throughresistance 65 at an exponential rate determined by the relative valuesof capacitance 64 and resistance 65.

When the voltage across resistance 65 exceeds a predetermined negativevalue, as, for example,

approximately -2 volts, electron discharge device 66 is in a state ofcutofi. Device 66 remains in the cutoff state for a period of timedetermined by the amplitude of the pulse voltage and the setting ofresistance 65. By varying the value of resistance 65, the period ofcutoff of device 66 may be varied, the degree of variation preferablybeing, for certain applications, from zero to approximatelymilliseconds. While device 66 is in a state of cutofi, the potential ofjunction point 92 assumes a positive value, preferably approximately 25volts, this value being achieved immediately as device 66 is cut oil.Since the time constant of capacitance 86 and resistance 8| is longcompared to the time constant of capacitance 64 and resistance 65, thevoltage across re sistance 8| is essentially constant while device 66 isin a state of cutoff. Thus the voltage across resistance 8| isessentially a square-wave pulse, the width or duration of which isdetermined principally by the setting of resistance 65.

This square-wave pulse of voltage is impressed on control electrode 81of device 82, which is rendered conductive thereby. Whether or notdevice 82 conducts, however, is dependent on rotary switch |2 whichunder certain conditions is arranged to provide a short circuit acrossdevice 82, and on contacts 96 the closing of which is necessary tocomplete the circuit of device 82. Whenever switch |2 is closed, windingof relay 53 is energized and contacts 96 are closed. It will be notedthat when contacts 96 are closed, contacts Hill of relay 53 are likewiseclosed. Contacts Hill are connected in a suitable loom-stopping circuitwhich is arranged to interrupt operation of the loom in response toopening of contacts I06. Thus for continuity of operaiton of the loom tobe maintained, it is necessary for relay 53 to be energized at alltimes.

Switch |2, which is opened and closed in response to motion ofcrankshaft 5, is closed during the greater portion of the loom cycle butis arranged to be open during the relatively short period during theloom cycle when shuttle normally passes in the vicinity of magneticdetector Hi. When switch I2 is opened during each loom cycle, therefore,it is necessary that device 82 be rendered conductive so that theactuating current for relay 53 previously flowing through switch |2 mayflow through device 82 and dropout of relay 53 does not occur. In otherwords, the signal from detector l9, which is responsive to passage ofshuttle II in the vicinity thereof and which render device 82conductive, must occur substantially in synchronism with cpening ofswitch I2, which is indicative of a predetermined point in the loomcycle, to prevent deenergization of relay 53 and stopping of the loom.

The detailed operation of the principal portions of the controlapparatus having beendescribed, the over-all operation of the apparatuswill now be considered to assist in the understanding of the invention.As shuttle II makes a flight across the loom a voltage pulse is providedby detector I through cooperative action of magnetic device I9therewith. The pulses obtained in this manner, however, are relativelyweak and are of variable magnitude and duration, making them generallyunsuited for rendering device 82 conductive. By the use of amplifier andpulse-shaper circuit substantially squarewave pulses are obtained, theduration of which may be varied by adjustment of resistance 65. Thesquare-wave pulses thus obtained are impressed on device 82 which isrendered conductive thereby. Device 82 does not conduct, however, unlessswitch I2 is open since the latter, when closed, short circuits device82.

Relay 53 is maintained closed during the greater portion of the loomcycle by switch I2. However, during a relatively short portion of thecycle switch I2 is open and relay 53 tends to drop out. It is during thiperiod that shuttle II in a normal flight passes in the vicinity ofdetector I0. I-f shuttle II is traveling normally the pulse signalprovided by detector I0 renders device 82 conductive prior to opening ofswitch I2. When the latter opens, device 82 conducts current to completethe circuit of relay 53 thereby preventing drop-out thereof. If device82 is of the gaseou discharge type, as is preferably the case,conduction therein, once initiated, continues even though the signalpulse dies out until the point in the loom cycle when switch I2 isclosed. Closing of the latter short circuits device 82 and preventsconduction thereby. Following dying out of the signal pulse and closingof switch I2, device 82 is no longer conductive and is thus ready forthe next loom cycle.

If the signal from detector III is out of synchronism with the openingof switch I2, device 82 is not rendered conductive at the proper timeand, when switch I2 opens, relay 53 is deenergized causing the loom tobe stopped. Although device 82 may be rendered conductive by a signalfrom detector I0 at a later than normal point in the loom cycle due tolateness of the shuttle in its flight, it will be noted that after relay53 is deenergized by opening of switch I2 contacts 88 are opened,thereby preventin the reclosing of relay 53 by device 82. Should theshuttle be too early in its flight, the signal pulse dies out by thetime switch I2 opens so that device 82 is no longer conductive, causingrelay 53 to be deenergized by opening of switch I2. It will be seen fromthe foregoing that it is necessary for the opening of switch I2, whichmay b regarded as instantaneous, to occur during the period when controlelectrode 81 of device 82 is provided with a potential which rendersdevice 82 conductive. Thus it is desirable to provide this Period with apredetermined duration, which is readily accomplished by the use of asquare-wave pulse. It is further desirable that this duration be readilyadjustable to take account of normal inconsistencies in shuttle traveland for loom conditions, which is accomplished conveniently byadjustment of resistance 65.

In the embodiment of my invention herein shown and described a singlemagnetic detecting device III, positioned approximately at the center oflay beam 4, is employed to detect motion of shuttle II. The use of asingle detector in this manner generally provides reliable and adequateindications of normal shuttle motion. Furthermore, the use of a singledetector at the mid-point of shuttle flight has the advantage 0!indicating faulty shuttle motion at a relatively early point in the loomcycle to allow maximum time for stopping the loom to prevent damage tothe fabric. In certain cases, however, it may be desirable to employmore than one detector located, for example, near the extremities of thelay beam. In such cases additional detector windings may readily beconnected in additional rectifier circuits similar to circuit 50, therectified signals therefrom being supplied to amplifier and pulseshapercircuit 5I in the manner previously described.

While I have shown and described a preferred embodiment of my invention,it will be under= sto'od that my invention may well take other forms andI, therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope oi the invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. For use in a weaving loom having a shuttle and means to move saidshuttle from an initial position in a flight toward a final positionduring each cycle of motion of said loom, said flight normally being ata predetermined velocity, electromagnetic means for providing a signalpulse responsive to passage of said shuttle in the vicinity of apredetermined point in said loom between said initial and finalpositions, means for providing a secondary pulse of predeterminedduration in response to said signal pulse, switching means responsive tomotion of said loom, said switching means being closed during asubstantial portion of said cycle of motion and open during theremainder of said cycle, opening of said switching means being efiectedat a predetermined time in said cycle, electromagnetic switching meansfor effecting stopping of said loom, said stopping being effected inresponse to deenergization of said electromagnetic switching means, andan electron discharge device having a cathode, an anode and a controlelectrode, said electron discharge device being rendered conductive inresponse to impressing of said secondary pulse on said controlelectrode, said firstmentioned switching means in the closed conditionthereof constituting a first means to efiect energization of saidelectromagnetic switching means and said electron discharge device beingconnected to form a second means to effect said energization when saidelectron discharge device is conductive, deenergization of saidelectromagnetic switching means and stopping of said loom being effectedin response to opening of said firstmentioned switching device prior tosaid electron discharge device being rendered conductive in response tosaid secondary pulse.

2. For use in a weaving loom having a shuttle and means to move saidshuttle from an initial position in a flight toward a final positionduring each cycle of motion of said loom, said flight normally being ata predetermined velocity, an electromagnetic device for providing asignal pulse responsive to passage of said shuttle in the vicinity of apredetermined point in said loom bewave pulse having a predeterminedduration, a

switch actuated in response to motion of said loom, said switch beingclosed during a substantial portion of said cycle and open during theremainder of said cycle, opening of said switch being eifected at apredetermined time in said cycle corresponding to the time in said cyclewhen said shuttle normally passes in the vicinity of said predeterminedpoint, an electromagnetic relay for eifecting stopping of said loom,said stopping being effected in response to deenergization of saidrelay, and an electron discharge device having a cathode, an anode and acontrol electrode, said electron discharge device being renderedconductive in response to impressing of said square-wave pulse on saidcontrol electrode, said switch in the closed condition thereofeonstituting a first conducting path to efiect energization of saidrelay and said electron discharge device being connected to form asecond conducting path to effect said energization, deenergization ofsaid relay and stopping of said loom being effected in response toopening of said switch prior to said electron discharge device beingrendered conductive in response to said square-wave pulse.

RICHARD W. WOLKE.

No references cited.

